Simulation of a system to determine the performance of the system and its individual constituents, is conventionally implemented by developing a customized model of the system. Then a customized program for implementing the model in a programmed computer is developed. This conventional approach is not only time consuming, but is also so specifically customized to a particular model, that change to the system in the iterative process of system development, requires a redesign and a re-code of the program. Moreover, because each program is customized, the results generated by two programs are not necessarily comparable.